Sheeting materials having a graphic image or other mark have been widely used, particularly as labels for authenticating an article or document. For example, one conventional imaged sheeting uses a high-gain retroreflective sheeting of the exposed-lens type in which images are formed by laser irradiation of the sheeting through a mask or pattern. That sheeting comprises a plurality of transparent glass microspheres partially embedded in a binder layer and partially exposed above the binder layer, with a metal reflective layer coated on the embedded surface of each of the plurality of microspheres. The binder layer contains carbon black, which is said to minimize any stray light that impinges on the sheeting while it is being imaged.
The energy of the laser beam is further concentrated by the focusing effect of the microlenses embedded in the binder layer. The images formed in this retroreflective sheeting can be viewed if, and only if, the sheeting is viewed from substantially the same angle at which the laser irradiation was directed at the sheeting. That means, in different terms, that the image is only viewable over a very limited observation angle.